TACX Connection to ANT+ HRM Strap

Hi,

upgraded to a TACX Flux S indoor trainer (from Vortex Wheel-On trainer) and having trouble getting TACX Desktop and TACX Android to recognise my Garmin ANT+ HRM Strap.  A recent firmware/software update saw the HR being recognised, but then suddenly it just stopped recognising it.  Annoying to see it get connected then suddenly decide not to connect.

Windows laptop with ANT+ dongle and Samsung Galaxy A51 (with ANT and ANT+ radios enabled).  My Garmin 735XT multisport watch finds the HRM strap, no bother, so the strap is fine.

Anybody have the same and got it fixed?

Cheers,

Pete